"(She) has been just an incredible supporter of my agenda. She's taken tough votes when they're the right thing to do, and she is somebody who I have counted on consistently," Obama, who endorsed Wasserman Schultz in March, said at a private DNC event in Miami, according to a transcript released by the White House.

He continued: "She's had my back. I want to make sure we have her back."

The Florida congresswoman has been under fire for months over her leadership of the DNC, as Bernie Sanders' campaign has alleged Wasserman Schultz has favored his presidential primary challenger, Hillary Clinton. Sanders and his supporters have complained about the nomination process and ways they believe it has helped Clinton, including debates held on Saturday nights, closed primaries in major states such as New York, and the use of superdelegates -- essentially free-agent party and union stalwarts who are overwhelmingly backing Clinton.

Last month, Sanders told CNN's Jake Tapper he supported Tim Canova, Wasserman Schultz's opponent in her August 30 primary, saying Canova's positions more closely aligned with his. He added that if he is elected president, he would effectively terminate her chairmanship of the DNC.